A boot is generally held in position on an alpine ski by means of bindings which hold its ends in place while permitting the release of one or the other of the ends when the boot generates excessive stress. Furthermore, the ends of the boot rest on support devices, or plates. To facilitate the release of the boot, use is normally made of support plates exhibiting low levels of friction.
In particular, the support plate used for the front end is encased in a covering made of an anti-friction material, most notably of polytetrafluorethylene, herein called PTFE.
Assembly of this covering to its support is a relatively tricky operation because of the anti-adhesive properties of PTFE. Moreover, the assembly must withstand climatic conditions to which the bindings are subjected i.e., snow, ultra-violet rays, temperature changes, etc.
French Patent Application No. 2,533,832 describes the bonding of these PTFE coverings using a double-sided adhesive or a cyanoacrylate- or isocyanate acrylic-type glue. For improved effectiveness and strength of the bond, the lower surface of the PTFE preliminarily undergoes surface pre-treatment, e.g., a treatment with sodium naphthalene or sodium ammonia. In addition, fillers are incorporated into the material composing the plate in order to slow the penetration of ultra-violet rays and deterioration of the bond.
This technique yields good results, but its implementation is relatively complex and costly.
French Patent Application No. 2,615,748 discloses a support device incorporating a covering made of PTFE, which is assembled to a support by a mechanical process such as latching, drawing, riveting, embedding, etc.
This technique has the advantage of making the bonding operation unnecessary. However, because the PTFE coverings are no longer glued, the assembly process must make it possible, first, to mount the coverings easily in their support, and second, to provide reliable position-retention of the coverings in their support.
In fact, when the binding is used in conjunction with a worn boot, the friction increases between the coverings and the boot sole. In this case, the boot must be prevented from drawing the covers laterally out of their supports.